1. Field of the Invention
This invention relates generally to heat engines and refrigeration apparatus and more particularly to a combination heat engine and cryogenic refrigeration apparatus that utilizes a low temperature heat source and a mixture of a non-condensable gas and a condensable gas to produce power and refrigeration simultaneously.
2. Brief Description of the Prior Art
The development of the 2nd Law of Thermodynamics is based primarily on heat engine analysis. The gist of Kelvin's statement of the 2nd Law Of Thermodynamics is that no cylic process is possible whose sole result is a flow of heat from a single reservoir and the performance of equivalent work.
It is known that any system operating on a cycle and receiving heat while doing work must also have a heat-rejection process as part of the cycle. A heat-rejection or heat-recuperation process may be make up in closed cycles with only a single external heat reservoir provided that the work medium is a combined mixture of a non-condensable first gas and a condensable second gas, wherein the condensable second gas is used as an internal cold reservoir to carry out the heat-rejection process and the non-condensable first is isothermally compressed and adiabatically expanded performing useful work. Therefore, it is possible to construct a heat engine which will do work and exchange heat with a single external heat reservoir.
The present invention employs a sliding-blade gas/liquid compressor operating in a closed cyle which effectively isothermally compresses a two-phase working medium mixture of gas and fine dispersed liquid (heat capacitance phase) which absorbs adiabatic heat in the compression process.
Most conventional high speed gas turbine compressor are not able to operate utilizing a two-phase gas/liquid medium since a liquid of the mixture produces destructive erosion of blades. In the present invention the liquid phase is not a destructive factor for the sliding-blade gas/liquid compressor, but instead, improves the compression process by providing the means for hydraulically packing the clearances.
Sliding-vane pumps are known in the art which are designed for performing a plurality of function in which vane radial travel is accomplished by the interaction between vane tips with the internal body bore. Ruzic, U.S. Pat. No. 5,144,802 discloses such a rotary fluid apparatus having pairs of connected vanes.
The principle disadvantage of such apparatus is that their design does not allow inlet and outlet channels at the full width of operating chambers which lowers its filling coefficient and leads to elevated hydrodynamic losses and also causes intensive wear of the vane tips. Moreover, lubricant is, present in the operating chamber which excludes it's application as a gas/liquid compressor.
Hiroshi et al, U.S. Pat. No. 5,044,910 discloses a vane pump with rotatable drive means for vanes wherein the vane tips are prevented from contacting the internal body bore. However, in this type of pump, the vane movement control means are positioned in the operating chambers and are not protected from interaction with the working medium. Moreover, the short vanes extend maximally in rotor slots and are subjected to large bending loads that subject the slot area to distortion and results in increased resistance as they slide in the slots.
Vane-type rotary pumps are also known in the art wherein the vanes are prevented from contacting the internal bore of the body. Chi, U.S. Pat. No. 5,385,458 discloses a vane-type rotary compressor. Eckharolt, U.S. Pat. No. 5,316,456 discloses a slide vane machine. Clerc, U.S. Pat. No. 2,562,698 discloses a rotary compressor having short vanes resting on rollers. Because of the large bending moment, such short vanes do not give full value positive effect.
One of the main disadvantages of the aforementioned apparatus is their intolerance of small amounts of liquids, because the critical surfaces of the structures requiring lubrication are not isolated from the working medium. For example, vane tips sliding over the fixed wall, vane movement control means and the like.
The sliding-blade gas/liquid compressor of the present invention overcomes the above described problems.